Anthranilate phosphoribosyl transferase catalyzes the second committed step in the synthesis of tryptophan. It is anticipated that anthranilate PRT will have a similar core structure to two related PRT enzymes, amido PRT and orotate PRT, a nucleotide fold, but due to its larger molecular weight the surface loop structure must be different. When it is solved, anthraniltate PRT will be the 5th enzyme of the Trp pathway to be elucidated by a crystal structure leaving only the first enzyme, anthranilate synthase.